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TUTORIALS
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Scalable and Localized
Network Layer Protocols in Ad Hoc and Sensor Networks The network layer problems can be divided into two groups: data communication, and topology control problems. In data communication problems, such as routing, quality-of-service routing, geocasting, multicasting, and broadcasting, the primary goal is to fulfil a given communication task successfully between nodes in ad hoc network. The secondary task is to minimize the communication overhead (since bandwidth in wireless communication is typically limited) and power consumption by battery operated nodes. Location updates for efficient routing are also covered. Topology control problems include neighbour discovery, determining transmission radii (fixed or adjustable), connectivity issues, partitioning for data replication, activity scheduling, Bluetooth scatternet formation problem (connected degree limited structure with nodes taking master and/or slave roles), finding a sparse connected structure (resembling minimal spanning trees), and finding connected dense planar structure. This tutorial will also review ongoing research on the ‘hot’ topic of sensor networks, including problems such as: physical properties, sensor training, medium access, sensor area coverage, object location, sensor position determination, routing, connectivity, data dissemination and gathering, data centric operations, and transport layer. The main paradigm shift is to apply localized (or
greedy) schemes as opposed to existing protocols requiring global
information. Localized algorithms are distributed algorithms where
simple local node behaviour achieves a desired global objective.
Localized protocols provide scalable solutions, that is, solutions for
wireless networks with an arbitrary number of nodes. |
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Wireless Sensor Networks:
Perspectives, Applications, and Research Directions Immense advances in wireless communications,
Micro-Electro-Mechanical Systems (MEMS), and optics have made possible
a future populated by small, low-power, cost-effective, autonomous
devices, termed sensor nodes, which will pervade society redefining the
way we live and work. Sensor nodes integrate sensing, special-purpose
computing and wireless communications. When networked, such sensor
nodes will form part of larger systems, providing data, offering
“services” and, as a whole, performing and controlling a multitude of
tasks and functions. Together with innovative network architectures
that will facilitate massive deployment, self-organization, unattended
operation, dynamic configuration, and sustained low power operation,
the small size and cost of individual sensor nodes will be a key
enabling ingredient for a large number of applications both in ordinary
as well as harsh environments. Given the utility of sensor networks in
environmental data collection, surveillance, and target tracking, they
can aid numerous applications as their requirements vary along the
time-space-context continuum. For example, in a large disaster prone
area, sensor networks may be employed throughout the lifecycle of major
events such as a fire, tornado or contamination outbreak. Sensor
networks can be used in support of preparation and prevention during
the pre-event phase, rapid response during the event, and post recovery
and analysis after the event. We envision, an area-of-interest (AoI),
where large numbers of miniaturized commodity sensor nodes are deployed
to instrument the environment, for example in buildings, on roads, in
vehicles, in the asphalt covering streets and roadways, etc. Sensor
nodes may be embedded in objects pervading the AoI, or deployed in a
non-pervasive manner. Deployment of new sensor nodes may take place on
demand at any time at designated locations or at random in specified
areas. |
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MEMS enabled Microsystems:
from dumb to cogent sensors-design for intelligence The aim of the tutorial is to present the directions of research, development and technological evolution for Electro Mechanical Microsystems, and in particular microsensors. The development of MEMS devices has generally followed a bottom up methodology, reaching now a stage where the capabilities of the devices could be used much more effectively in systems designed from the top down to include them. A holistic view of the requirements of MEMS based systems and the capabilities of the microdevices must be taken if such systems are to deliver the promise that was expected. This tutorial provides the integrative perspective required for workers in all areas of the field, to enable them to appreciate the system level design issues leading to breakthrough sensing applications. The tutorial would be of interest to MEMS and nanodevices technologists/designers/ developers, specialists working at system level in sensors and sensor networks and application developers considering the use of MEMS devices as part of high-level intelligent systems, who will need to understand the opportunities and constraints brought by MEMS technology. Synopsis: Microsensors are particularly buoyant sector in the industry of man-made complex machines. Traditionally, the main sensor requirements (linearly transferred from the macro sensors industry to the micromachining technologies) were in terms of metrological performance, i.e. the (most often) electrical signal produced by the sensor needed to match relatively accurately the measurand. Such basic sensor functionality is no longer sufficient. The nature of industry demand, and therefore the research goals of the sensing community are presently shifting, away from aiming to design perfect mono-function transducers towards the utilization MEMS based sensors as system components. A new set of requirements for sensing systems and more generally for measurement systems is therefore being generated. Such requirements ultimately imply that components are enhanced with increasingly autonomous functional capabilities. It is here, in the area of data processing and extraction of information, that the author proposes to situate the core of the tutorial, expanding both ways: towards the sensing devices themselves and the MEMS technology which enables their production and towards the application end of the enhanced sensing systems. The presentation clarifies the strands of development in sensing, some of which are linked with the industry demand for “replacement products” (process/instrumentation sensors designed for high accuracy or cheap/minimum size& weight/minimal electronics sensors for liberal use in appliances and automotive industry for example), whilst other strands are under development either to enable new applications or to support the dreams of future machines ( for example large networks of sensors exhibiting collective behaviour and ultimately cogent sensing to enable cogent actuation and eternal vehicles). The evolution process is discussed from a system requirements perspective and supported by an analysis of the components which make a sensor/sensor system, from the simplest such sensor performing straight forward metrology through the self-testing sensor to the fully fledged cogent sensor which can autonomously make informed decisions on the data and perform complex information transformations. The hardware and software requirements of the sensors along this line will be discussed and example implementations will be shown. The newer pool of potential “big” sensors applications need more than MEMS device technology perfection - the inherent, natural MEMS properties of size and potentially low cost encouraged the liberal usage of these devices in applications (smart skin with thousands of devices embedded, deployable sensor webs, etc) which in turn lead to the need to rely on/add efficient and clever processing of data generated by the sensing device, before such data reaches the outer world. Technology perfection might not, therefore, be, in the new light, the primary aim in developing successful MEMS sensors and particularly sensor systems. Since signal processing is needed anyway by the sensing application, most imperfections could also be, potentially, compensated for in the software/hardware associated/integrated with the sensor, as long as the integration of sensor and processing is resolved. Attendees will gain the perspective and context of
the field in order to make design decisions which optimally utilize
current and forthcoming developments in these technologies. |
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Directional Antenna Systems
for Mobile Ad Hoc and Sensor Networks Mobile Ad Hoc Networks (MANETs) and Sensor Networks
(SNs) employing omni-directional antennas are known to suffer from poor
network performance due to multi-hop forwarding requirements and
insufficient spatial reuse. The root of this problem is that
traditional MAC and routing protocols being used for these networks
assume omni-directional antennas for communication at the physical
layer. |
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